Three international mining experts agree it is possible to re-enter the Pike River coalmine to retrieve the bodies of 29 men killed in the November 2010 blast.

Mining consultant Bob Stevenson and mining engineer David Creedy, both of England, and Kiwi mine-safety expert Dave Feickert spent this week in Greymouth at the request of the victims' families to review the feasibility of a mine re-entry plan.

''It is our belief as a group that yes, we can in fact effect a re-entry into these workings and we can do it safely. It's not without problems, but we believe those problems are solvable,'' Stevenson, a former principal mines inspector with 50 years' mining experience, said today.

The first step involved entering the 2.3-kilometre tunnel in stages up to a rockfall near the far end.

If that proved passable, a recovery team would enter the mine's main working area, where most, if not all, of the bodies remained.

Otherwise, a new tunnel would be bored around the rockfall to gain access to the bodies.

''We'd be even more happy if we knew it was actually going to happen.''

Their plan needed support from Solid Energy, the mine's new owner, Mines Rescue Service, the Government and the public because it could end up being funded by their taxes.

''At some stage, someone has to put their hand in their pocket,'' Stevenson said.

''My view is this - if there were 29 US astronauts stuck on the Moon and you've got a 300,000-mile irrespirable atmosphere between us and them, we'd get them.''

The group visited Pike River this week and walked up to a temporary seal about 170 metres along the underground coalmine's tunnel, which proved an emotional experience.

When the seal was built in July last year, Mines Rescue Service workers stuck a note on it to the 29 men, saying it was the first step towards getting their bodies home.

''I found it extremely upsetting,'' Stevenson said, admitting he wept when he read the letter.

''When I first got in the mine, it was almost an eerie feeling to start with, and then it begins to feel like it's an ordinary mine,'' Creedy said.

''The notice brings it all sharply in focus again what it's all about. After we read that, I think that strengthened our determination that we've got this plan, let's get behind it and try to make it work.''

They also visited a memorial garden near the road turnoff to the mine, which was also poignant.

The group arrived in time for Monday's release of the royal commission's report into the tragedy, which harshly criticised mine management and government agencies, including New Zealand's health and safety laws.

Bernie Monk, spokesman for most Pike families, was cautiously optimistic a body recovery would go ahead and planned to present the expert's re-entry plan to Solid Energy and Prime Minister John Key once completed.

He phoned Solid Energy chief executive Don Elder to inform him of their conclusions.

Monk, who lost his son Michael in the blast, said Key always told families if they produced a safe and credible recovery plan, money was not an issue.

The experts gave their time to the families for free but their trip was funded by the Climate Change Foundation to write a case study for the United Nations about the tragedy ''to ensure the lessons are viewed with a more international perspective''.